Thermodynamics of the structural transition in metal-organic frameworks.

A thermodynamic study of the structural large-pore (LP) to narrow pore (NP) transition in various Metal Organic Frameworks (MOFs) is presented. First, the pressure induced transition at a constant temperature is investigated using a Tian-Calvet microcalorimeter set-up equipped with a high pressure cell. This device permits simultaneous measurements of the mechanical work and heat associated with the LP → NP transition. It is shown that MIL-53(Al) and MIL-53(Cr) have similar thermodynamic and mechanical behaviour whilst the MIL-47(V) system is characterized by much higher transition energy and mechanical work. Second, the temperature induced transition at ambient pressure is studied by means of differential scanning calorimetry (DSC) combined with X-ray absorption spectroscopy. This set-up enables one to follow simultaneously the structural changes associated with the phase transition detected by DSC. The MIL-53(Cr)-Br functionalized MOF is chosen here as a case study where both energetics and structural changes are discussed.

Application of neural network calibrations to an halide ISE array.

The Neural Network (NN) technique was applied to the calibration of an ion selective electrode (ISE) array comprising a bromide selective electrode, two chloride ISEs and one thiocyanate ISE. The measured samples were synthetic mixture solutions of chlorides and bromides in concentration ranges such that interference occurs. The NN method allowed to perform the calibration without estimating the coefficients of the Nikolskii-Eisenman theoretical relation. Only the determination of bromide was detailed. The results obtained using this method were better than those obtained using linear multivariate calibration methods.

Reactivity of NASICON with water and interpretation of the detection limit of a NASICON based Na(+) ion selective electrode.

The leaching of Na(+) ions from NASICON of composition Na(3)Zr(2)Si(2)PO(12) to the aqueous solution was evidenced. The origin of the Na(+) leaching was studied using Na(+) concentration and pH measurements as well as solution and X-ray analyses. The Na(+) released was mainly attributed to the dissolution of a second phase, predominantly amorphous. The rate of Na(+) release was found to be dependent on the inverse of the square of the particle size. It is proposed that it is controlled by diffusion within the particle. An effective diffusion coefficient was deduced to be of the order of 5x10(-10) cm(2) s(-1). The nature of the detection limit of the NASICON based Na(+) ion selective electrodes is discussed.

Halide ion-selective electrode array calibration.

The calibration of several ions (Cl(-), Br(-), F(-) and OH(-)) measured with an ion selective electrodes (ISE) array has been carried out in the presence of interferents using an experimental design and multivariate calibration methods. Partial least squares regression and principal component regression do not seem to improve the test set prediction compared to multivariate linear regression. In the case of very slight or no interference on the ISE, each ion can be determined using the corresponding ISE and univariate calibration methods, but the use of multivariate methods does not lead to worse results.

Non-polarisable dry electrode based on NASICON ceramic.

A NASICON-type ceramic (high sodium ion conductor) is proposed to record bioelectric signals. The electrode does not need gel before its application. The principle of the measurements is based on a sodium ion exchange between the skin and the material. Electrical measurements performed in saline solutions show that the electrode is slightly polarisable. The skin-electrode impedance was investigated. The impedance decreases as a function of the time of application. The resistive component is the major source of the impedance change. This can be explained by the perspiration process which occurs immediately with time after the application of the NASICON-based electrode on the skin. The skin condition is also an important parameter. NaCl saline solution or abrasion causes the resistance to decrease markedly.

Sucrose induced hypertriglyceridaemia: its mechanism and metabolic effects.

The study summarizes the metabolic effects of increased sucrose or fructose intake. Compared with the traditional carbohydrate source-starch, a high intake of the above two carbohydrates produces a number of metabolic and other changes that can have a pathological effect. A thus induced metabolic and other changes that can have hepatic lipid synthesis, hypertriglyceridaemia and increased tissue lipid utilization, while tissue glucose utilization decreases. Moreover, the increase of these carbohydrates can lead to some pathological organ changes and elevation of blood pressure.

Initial vascular changes and their pharmacological management in atherosclerosis induced by immunological injury and hyperlipidaemia.

The authors studied the pathophysiological mechanisms the early stages of atherosclerosis induced by immunization in combination with short-term intake of dietary cholesterol. The mechanisms involved in the development of lesions comprised impaired endothelial integrity, increased permeability and transmural protein transport in the aorta. The changes were induced by the combined synergic action of immunization and cholesterol diet. Further, their study showed that progression of the thus induced atherosclerotic lesions can be inhibited by histamine and serotonin antagonists. The fact that the latter decreased the extent of endothelial injury, permeability and cholesterol accumulation in the aorta without changing the level of cholesterolaemia indicate that drugs are capable of controlling the pathophysiological processes in the artery participating in atherosclerotic lesions.

Palmitate and glucose oxidation by diaphragm of rats with fructose-induced hypertriglyceridemia.

Palmitate and glucose oxidation were investigated in isolated hemidiaphragm of rats in which hypertriglyceridemia was induced by dietary fructose. Palmitate oxidation was increased, and glucose oxidation was reduced, in fructose-fed rats, as compared with glucose-fed controls. Glucose incorporation into muscle glycogen was similar in both dietary groups.

Liver glycogen synthesis and glucose tolerance in rats adapted to diets with a high proportion of fructose or glucose.

Glucose tolerance and in vivo incorporation of glucose into liver glycogen were investigated in rats fed high carbohydrate diets containing glucose or fructose as the sole carbohydrate source. As compared with control glucose-adapted rats, a slight deterioration of the glucose tolerance was observed in fructose-adapted rats. The possivle cause of the deteriorated glucose tolerance in fructose-adapted rats seems to be among others reduced glucose incorporation into liver glycogen and a smaller depression of endogenous glucose production by exogenous glucose.

Effect of the type and proportion of dietary carbohydrate on serum glucose levels and liver and muscle glycogen synthesis in the rat.

The effect of the type of dietary carbohydrate on oral glucose tolerance and on in vivo incorporation of labeled glucose or fructose into liver and muscle glycogen in the rat were investigated. The intake of fructose or sucrose reduced, as compared with starch or glucose, glucose incorporation into liver glycogen and caused a slight deterioration of the glucose tolerance. These effects were observed already when 50% of the total dietary carbohydrate was substituted by fructose or sucrose. The incorporation of labeled glucose into muscle glycogen was not affected by the type of dietary carbohydrate. Specific radioactivity of liver and muscle glycogen and the concentration of muscle glycogen after administration of labeled fructose were higher in fructose-adapted than in glucose-adapted rats.

Teaching foster grandparents to train severely handicapped persons.

Five foster grandparents were taught training skills for use in their daily interactions with severely handicapped persons in an institution. Following baseline, specific teaching procedures consisting of teacher instructions, prompts, modelling, and praise were implemented. The grandparents' frequency of training three skill areas increased as the specific teaching was implemented in multiple-baseline format. The total amount of training continued as teacher instructions, prompts, and modelling were terminated and praise continued, although the grandparents spent their training time emphasizing only two of the three skill areas. Teacher presence was gradually reduced over an 11-week period, with no decrease in grandparents' frequency of training. Four of the foster grandchildren, all profoundly retarded and multiply handicapped, demonstrated progress throughout the study. Results were discussed in light of the available contributions of foster grandparents in institutional settings and maintenance of staff training.

Diet-induced adaptation of intestinal fructose absorption in the rat.

The effect of dietary sucrose, fructose and glucose on the intestinal absorption of fructose and glucose was investigated in adult rats in vivo: Glucose absorption was not affected by the type of dietary carbohydrate, while the absorption of fructose was increased by the ingestion of the sucrose or fructose diet, as compared with the glucose diet. An almost maximal increase of fructose absorption was already observed when the quarter of the total dietary carbohydrates was replaced by fructose. Faecal fructose elimination declined during the feeding experiment. The enhanced intestinal absorption of the fructose load in rats fed the fructose diet was manifested by higher concentrations of fructose, but also of glucose and lactate in the hepatic portal blood.

The effect of cyclophosphamide on compensatory hypertrophy and some renal functions in rats.

Administration of 20 mg/kg cyclophosphamide to unilaterally nephrectomized rats for a period of two weeks significantly increased the ratio of kidney weight to total body weight. This rise is, however, accountable more by the decrease of total body weight than by weight increase of the kidney. The RNA-DNA ratio in the hyperttrophic kidney after cyclophosphamide did not differ significantly from that found in the hyperttrophic kidneys of controls. The results obtained show that in our experimental lay-out cyclophosphamide did not inhibit significantly the compensatory renal hypettrophy. After cyclophosphamide, the hypertrophic kidney produced urine with lower concentrations of endogenous creatinine, all osmotically active substances and potassium than found in controls.